The shrub Zanthoxylum americanum has compound, alternate leaves and stout, paired thorns at each node. The only other woody species in our flora with that combination is the tree Robinia pseudoacacia (black locust). Zanthoxylum can be distinguished by its pointed leaflets and the presence of a few thorns on the underside of the leaf midrib. Robinia pseudoacacia has blunt tipped leaflets and no thorns on the leaf midrib. Also the buds are very different. The buds of Robinia pseudoacacia are hidden beneath the leaf scar, while those of Zanthozylum are large, covered with reddish hairs and easily visible above the leaf scar.